Core-valence ionization correlation

Copper-zinc reagents, in asymmetric addition reactions, 9, 110 Core-functionalized dendrimers as catalyst hosts, 12, 803 as organometallic hosts, 12, 800 Core-valence ionization correlations, and photoelectron spectroscopy, 1, 394... 

Ligand Additivity Effects, Ligand Field Effects, and Core-Valence Ionization Correlations... 

The active space used for both systems in these calculations is sufficiently large to incorporate important core-core, core-valence, and valence-valence electron correlation, and hence should be capable of providing a reliable estimate of Wj- In addition to the P,T-odd interaction constant Wd, we also compute ground to excited state transition energies, the ionization potential, dipole moment (pe), ground state equilibrium bond length and vibrational frequency (ov) for the YbF and pe for the BaF molecule. 

Another approach of this kind uses the approximate Brueckner orbitals from a so-called Brueckner doubles, coupled-cluster calculation [39, 40]. Methods of this kind are distinguished by their versatility and have been applied to valence ionization energies of closed-shell molecules, electron detachment energies of highly correlated anions, core ionization... 

In earlier papers [6-8] we have proposed a procedure for evaluating core ioniza-tion/excitation chemical shifts in molecules from computed core ionization/excitation energies for the relevant isolated atom in neutral and valence-ionized states and from computed charge transfer relative to this atom within the molecule. The atomic calculations involved relaxation, possibly correlation and, when appropriate, relativity and other effects, while in the molecule one could use any approximate method (possibly involving effective core potentials) yielding reliable charges. 

Though there is no correlation in either calculation, the core relaxation effect accounts for an enormous improvement (7.34 eV). For the valence ionizations, though, this is not as pronounced, although the results are improved over... 

To improve on both SCF approximations, correlation is essential. Such results are shown in Table 17. Note that correlation effects amount to more than 1 eV for the valence ionizations, which also corrects the order, while the effect on the core ionization is about 8 eV. 

Figure 15. First (IPj) and second (IP2) ionization potentials of the lanthanide elements j La -2jLu. Experimental values are compared to results from 4f-in-core pseudopotential (PP) calculations with and without account of core-valence correlation effects by means of a core polarization potential (CPP) [95].

Several empirical corrections are added to the resulting energies in the CBS methods to remove the systematic errors in the calculations. The CBS-Q method contains a two-electron correction term similar in spirit to the higher-level correction used in G2 theory, a spin correction term to account for errors resulting from spin contamination in UHF wavefunctions for open shell systems, and a correction to the Na atom to account for core-valence correlation effects. The CBS-4 and CBS-q methods also contain a one-electron correction term to improve the computed ionization energies and electron affinities. The mean absolute deviation for the 125 energies in the G2 test set is 2.0 kcal mol (CBS-4), 1.7 kcal mol (CBS-q), and 1.0 kcal mol (CBS-Q), respectively. These methods have not yet been tested for the 148 molecules in the enlarged G2 test set. 

Configuration Interaction Core-Valence Correlation Effects Dynamic Properties Electron-Molecule Scattering Electronic Wavefunctions Analysis Green s Function Ionization Potentials in Semiempirical MO Theory M0l-ler-Plesset Perturbation Theory Pseudospectral Methods in Ab Initio Quantum Chemistry Spectroscopy Computational Methods Time Correlation Functions. 

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